Help on Sorting

Hello Everyone, I need help here . I need to sort a file for one of my requirement , The file has to be sorted using a key with 4 columns. Sorting is working fine on those 4 columns but when the key is matching for many rows the other columns are also getting sorted which is not required .

Giving an example here : File = Input.txt

1 101 100 
1 001 200
1 002 100

Here I am using below command to sort.

Sort -k1,1 -k3  Input.txt

This gives me below output:

1 002  100
1 101 100
1 001 200

I don't want to sort the second column here . I have tried with -s option for stable sort but the same is not supported .

Please help.

Hi, try

sort -Vr

and use option --debug for testing

--- Post updated at 19:22 ---

sort -k1,3.4 --debug

I dealt with something like this before. I had to add an extra column, which held the line number, like:

1 101 100 1
1 001 200 2
1 002 100 3

...so that I could give that column number to sort, forcing groups of lines back into file order after other sorting conditions were satisfied.

$ awk '{ $(NF+1)=NR } 1' < inputfile | sort -k1,1 -k 3 -k 4

1 101 100 1
1 002 100 3
1 001 200 2

$ awk '{ $(NF+1)=NR } 1' < data | sort -k1,1 -k 3 -k 4 | cut -d ' ' -f 1,2,3

1 101 100
1 002 100
1 001 200

$

The result you get is exactly as specified - sorted by field 1 (all lines identical), then field 3. I don't see column 2 sorted - it's just random, as its results are unspecified. To keep the original file order once all keys are consumed, try Corona688's approach, or, quite similar:

cat -n file3 | sort -b -k2,2 -k4n -k1,1 | cut -f2-
1 101 100 
1 002 100
1 001 200

The problem with your sample file is a trailing space in line one that influences the key 4 - use -n to overcome.

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I think the order of not-sorted columns is not defined. The usual algorithms seem to sort them to the lowest degree.
GNU sort has the --stable option:

sort --stable -k1,1 -k3,3 input.txt

Tried this .. Getting error that option is not supported

--- Post updated at 04:32 AM ---

I have 12 input files for this requirement .. Do I need to add the number in each file .. even if I do the key will match for multiple rows.

Hi. How to handle this when I have more than one input file

--- Post updated at 11:10 AM ---

HI .. How to handle this case when I have multiple input files

If you want 12 output files you need to treat them separately, and a loop is appropriate.

for file in input1.txt input2.txt ...
do
  cat -n "$file" | sort -k2,2 -k4,4 -k1,1 | cut -f2- > "$file".sorted
done

Hi .. Output file is only one and input files are more than one. I need to sort them and merge into one file. When the keys in files matching, the sorting is not working fine . It is sorting based on other columns also which are not part of key. My question is if I add number in each file at the end to solve this, How will it work as in each file number will be added at the end.

--- Post updated at 04:03 PM ---

Hi .. I am able to apply this logic in one input file. In my scenario the input files are more than one . All of them to be sorted and generate one output file. Please help how to achieve this .
I have tried the option of combining the files in one Temporary file and in that temporary file I am applying this logic mentioned by you to generate final output.

Is there any other way.

cat -n starts from 1 with each file, so awk with its NR is better:

awk '{print (NR "\t" $0)}' input1.txt input2.txt ... | sort -k2,2 -k4,4 -k1,1 | cut -f2-

Note: the awk inserts a tab-separated field #1, so the sort fields are +1 compared to the fields in the input files. At the end the field #1 is cut off again.

Can I apply this logic to more than one input file at a time??

--- Post updated at 05:07 PM ---

It is working now ., Thank you for help.